The spray’s key ingredient, capsaicin—the organic compound that makes peppers spicy—irritates a bear’s sensory organs, causing mild asphyxiation. Most bears do not make a close enough approach to the capsaicin vapor to suffer, however.

The sight and sound of the gas alone could be enough to scare off the bear, says Brigham Young University biologist Tom Smith, the chief author of the findings.

Sprays are preferable to shooting from a preservation aspect as well. If hunters used sprays as a bear deterrent the bears would stay alive, plus "they would know that this red-hot spray stuff will be really nasty and to avoid it … Bears are smart,” said Brian Peck of the Great Bear Foundation.

Running away is usually enough to escape from alligators and crocodiles, as they will only chase a human for about 30 feet. If attacked, a bump on the snout and playing dead is the best course of action for the victim.

Contrary to popular opinion, hitting a shark on its nose is not the best course of action during an attack, according to survival website Worst Case Scenarios. Instead, poking its eyes and gills is the best way to fend off a shark.

"The probability is the bear spray will outperform a firearm and it's easy to see why. The spray is easy to deploy. The rifle is just difficult to use,” says Brigham Young University biologist Tom Smith.

Smith says that sprays give humans a way to defend themselves in a manner that does not depend on size for effectiveness. “Having seen bears with porcupine quills in their faces, I'm sure that most bears learn at an early age that size is not a good indicator of threat,” he says.

Pepper sprays meant for use against human attackers are ineffective against bears. The sprays should be used when the bear is about 40 to 60 feet away, using a side-to-side motion to create a vapor cloud. The nozzle should be depressed for at least six seconds. If the bear continues to charge, the cloud of pepper spray will cause the bear’s mouth to foam up, its throat to contract and deaden its sense of smell. Spray residue on equipment can attract bears, however.

Although shark attacks are very rare, beach enthusiasts can minimize their chances of encountering them if they stay in groups while in the water, as sharks prefer to go after solitary prey. Swimming in water with lower underwater visibility, such as swimming at night or in water clouded with sand, gives sharks a sensory advantage over humans and should be avoided. High-contrast swimsuits and flashy jewelry can attract sharks, as the color scheme reminds them of fish, their natural prey. Blood stimulates sharks’ smell, so swimming with open cuts is inadvisable.

The best way to scare a shark is to fight back, using anything at arm’s reach—a camera, a stick or a fist—to hit it repeatedly in its eyes and gills, the most sensitive part of its face. Unless the eyes or gills cannot be reached, a shark’s snout is not the optimum place to strike in order to fend it off.

A kayaker’s best course of defense against a shark is to whack its snout with a paddle, writes TopKayak.org. Should the kayak topple, keep hold of the paddle, get back into the boat, and row quickly as possible to shore. If getting back aboard is impossible, kayakers should back up against something to limit the shark’s direction of attack.

If an alligator comes charging, the recommended course of action is to run away in a straight line. It will only run after a human for 30 feet. If the alligator manages to chomp down on you, hit it on the nose rather than try to pry its jaws open. Travel site Bugbog gives the same advice, in addition to playing dead, for defense against crocodiles.

The International Wolf Center writes in a PDF that the best way to scare off wolves is to raise and wave the arms to give the appearance of being larger. Making noise and throwing objects at the wolf while slowly backing away is also helpful.

The National Parks Service has a tip sheet on bear safety in Alaska. Words of advice include leaving pets at home during camping trips, disposing of food scraps and wearing a bell when hiking to make noise.